That’s a tough one. The Bible might be a cliché answer, but it continues to change my life on a regular basis as I read more of it. There have been many. Mere Christianity (Lewis) influenced the way I see religion. Why Black People Tend To Shout shaped my views on race. A Light In The Forest helped me identify myself within my rather confusing surroundings. I read a great deal of Asimov and Heinlein, when I was young, which helped shape my view of technology and the future.
Ask me another question, I’ll be honest.